The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.
In cellular mobile communication, frequency spectrum is divided into non-overlapping spectrum bands which are assigned to different cells. However, after certain geographical distance, the frequency bands are reused, i.e. the same spectrum bands are re-assigned to other distant cells. Besides signals within the cell, signals at the same frequencies arrive at the receiver from undesired transmitters located in some other cells and may lead to deterioration in receiver performance. Originally, communications systems have been planned to cope with intra-system interference; e.g. frequency reuse and frequency hopping methods have been used in GSM system. Moreover, intra-system interference may be controlled with various radio resource management methods. However, a problem arises when different radio technologies are operating on the same frequency resources on nearby cells.